1. Field of the Invention
This invention relates generally to retroperfusion catheters and methods, and more specifically to such apparatus and methods particularly adapted for use in perfusing ischemic brain tissue.
2. Discussion of the Prior Art
Tissue of the human body is maintained viable with oxygen which is delivered to the body in blood which is pumped through a labyrinth of vessels by the heart. Initially, the blood is pumped into arteries which direct it into capillary beds throughout the tissue. Oxygen is removed from the blood by the tissue surrounding these capillary beds.
The deoxygenated blood is collected from the capillary beds and returned to the heart through veins. The blood is then reoxygenated in the lungs and pumped back out through the arteries by the heart.
In the head, the oxygenated blood is carried by the carotid and vertebral arteries which ultimately deliver the oxygenated blood to capillary beds in the brain. The deoxygenated blood is collected from the capillary beds and returned through the jugular veins to the heart.
Stroke most often occurs in a patient when an embolus is carried into one of the arteries in the head. In these narrowing arteries, the embolus becomes lodged, blocking the flow of oxygenated blood to the downstream capillary beds. Without the life-sustaining oxygen and other essential blood components, these capillary beds become ischemic and the brain tissue degenerates, causing the stroke.
For decades, medical investigators have unsuccessfully sought to develop an early treatment for ischemic brain stroke. It has been appreciated that the more quickly one addresses the lack of oxygen in the brain, the more likely it is that the degeneration of the tissue can be prevented and the stroke avoided.
A system and method of cerebral retroperfusion is disclosed and claimed in applicant's copending application, Ser. No. 08/757,303, filed on Nov. 27, 1996, now U.S. Pat. No. 5,794,629 and entitled, "Method for Treating Ischemic Brain Stroke." This application is incorporated herein by reference. In this document, applicant discloses a system involving multiple catheters which are used to at least partially occlude the jugular veins while continuously pumping arterial blood into one or both of the cerebral sinuses. The multiple catheters disclosed for use in this system have required separate placement and operation in order to achieve both the occlusion and retroperfusion aspects of the procedure. The retroperfusion by these catheters has been achieved by way of a through-lumen which exits the distal tip of at least one of the catheters. This through-lumen is readily available as its secondary purpose is to facilitate placement of the catheter over a guidewire. Once the guidewire is removed, the through-lumen can be used to facilitate perfusion.